Classroom rugs in the city’s public schools are filthy health hazards contaminated with high levels of dust, germs and even fiberglass because they’re not cleaned regularly, a bombshell study by the teachers union charged.

The United Federation of Teachers said the dirty, bacteria-laden rugs are particularly unhealthy for students and teachers with asthma or allergies.

“Rugs are supposed to be comfort zones. This comfort zone has become a contaminated zone,” said UFT president Randi Weingarten.

After hearing teacher complaints, the teachers’ union hired an environmental firm to test the carpets in nine elementary schools throughout the city: PS 75 and PS 194 in Manhattan; PS 7 and PS 89 in Queens; PS 1, PS 78 and PS 119 in The Bronx; and PS 229 and PS 3 in Brooklyn.

The results showed that virtually every classroom tested had “excessive” levels of dust.

Fiberglass, which can cause skin rashes and irritate the respiratory system, was found in the rugs in PS 3 in Brooklyn and PS 89 in Queens.

Mouse droppings were visible in some classrooms, the study said.

Department of Education officials did not dispute the findings, and said all the rugs will be vacuumed and “steam-cleaned” during winter recess next week.